1. Field of the Invention
The present invention generally relates to a semiconductor module and method for forming the same. Specifically, the present invention provides a semiconductor module having an interposer structure with metallurgical through connections for electrically connecting a semiconductor chip to a substrate.
2. Related Art
In the production of semiconductor modules, a semiconductor chip is often connected to a carrier such as a substrate. Typically, the connection is made using controlled collapse chip connection (C4) technology whereby solder bumps are used to join the two components together. Unfortunately, several problems emerge with the existing technology. First, the semiconductor chip usually has a different coefficient of thermal expansion (CTE) than the substrate. Given the close physical proximity of the semiconductor chip to the substrate, the solder bumps often deteriorate as the module heats up and cools off. This is especially the case with larger die sizes.
In addition, ceramic substrates (if used) are generally non-planar, which can become a gating factor as the substrate X-Y dimensions increase. With shrinking pitch, there is a need to shrink C4 bump dimensions to avoid nearest neighbor shorting. However, a small C4 bump height results in a larger percentage of variation across the grid of bumps. Further, when the interconnections at the chip to substrate level migrate to a lead-free system, there will be no solder temperature hierarchy between first and second level interconnections, thus, creating an increased strain on the C4 structure due to higher temperatures of subsequent assembly operations. Still yet, current methods of depositing and joining C4 interconnections are expensive and involve the use of specific under bump metallization (UBM), which might have to be customized. Also, the UBM may need additional layers such as diffusion barriers and chip encapsulants so that it may endure a melting or partially melting C4 structure that reacts with the UBM during subsequent assembly operations.
In view of the foregoing, there exists a need for an improved semiconductor module and method for forming the same. Specifically, a need exists for a semiconductor chip to be electrically connected to a substrate or the like so that the above concerns are alleviated.